Our overall goal is to obtain a better understanding of neurochemical integration of various inputs in the paratracheal parasympathetic nerve-ganglion plexus. We propose experiments which are expected to provide answers to questions concerning the presence of various neuropeptides and monoamines in neurons and nerve terminals in this plexus, whether these substances could function as neurotransmitters or modulators and the nature of microcircuitry in this plexus. The proposed experiments will utilize immunocytochemical techniques to examine the spectrum of neuropeptides and monoamines and their distribution, as studied with light and electron microscopy. This approach will be followed by unique experiments where we will combine cell labeling techniques, electrophysiological measurements and immunocytochemical techniques, which should allow description of immunoreactive neuropeptides and monoamines in the soma of physiologically identified neurons and the nature of immunoreactive compounds in axon terminals synapsing on these neurons. In addition, two tracer experiments will give additional evidence about the type of ganglion cells that provide axon terminals to other physiologically identified neurons. We will also perform studies on the effects of neuropeptides and monoamines, found to be present in this plexus on (a) electrical properties of AH and type B ganglion cells, (b) evoked post-synaptic potentials (PSPs) and (c) neurotransmission. Comparison of these data and data obtained studying evoked PSPs will be useful in determining the physiological actions of putative neuropeptides and monoamines in this plexus. These studies will be extended in experiments where the effects of specific antibodies to neuropeptides and monoamines on evoked PSPs will be determined. These studies are unique in the sense that they represent the first approach to neurointegration in the parasympathetic ganglion supplying airways. The combined approach of developing descriptions of microcircuits complete with putative neurotransmitters or modulators and studying electrophysiological evidence for functions of these compounds, should add to our understanding of the nature of the integrative neuronal circuitry in this nerve-ganglion plexus.